1. Field of the Invention
This invention relates to refrigeration and specifically to the efficient cooling of freshly picked vegetables from the field.
2. Description of Related Art
When produce, such as strawberries, cauliflower, cabbage, and the like, is harvested, workers in the field will pack the produce in cartons. These cartons or boxes are typically rectangular in shape and normally have side openings for facilitating holding of the cartons. Typically the cartons are stacked on pallets and the stacked cartons are in turn then transferred to a flat bed truck or other transportation means to be shipped to a distribution point.
The shelf life of most produce is a function of how quickly the field heat can be removed from the produce once it has been harvested. If considerable time lapses from the time of harvesting to the time of initial cooling down of the produce, the overall shelf life at a retail store is substantially reduced. Any system which will speed up the process of pre-cooling or removing the field heat from the produce after harvesting, or which will increase the efficiency or reliability of machinery involved in such cooling, will have significant economic benefit.
In U.S. Pat. No. 4,474,020, to Freeman, a cooling chamber for drawing down freshly picked and field warmed vegetables is disclosed. A group of individual pallets loaded with rectangular cartons of produce are placed in the field on a transport chassis and brought to the vicinity of the cooling chamber where they are simultaneously unloaded by a multi-pallet forklift truck. The chamber receives this multi-pallet load through an open door and a rear seal conforms to the periphery of the load to define a warm air return plenum. The main chamber door is closed to define a high pressure cool air plenum. Circulation of forced and cooled air occurs for rapid drawing down of the palletized load to a curing temperature.
In U.S. Pat. No. 4,736,592, Ohling, an apparatus for directing cool air to stacks of containers holding freshly harvested produce to remove field heat is disclosed. The apparatus includes a housing having a suction fan for blowing air through an air cooler into a plenum from which the cool air passes through the containers of produce. The direction of the airflow is selectable by moving damper devices relative to the housing.
A drawback of the prior art devices mentioned above is that the containers must be loaded and removed from the same entrance door area. Another drawback is that the devices are not readily adapted to work with differing sizes of pallets or differing sizes of stacks on pallets. A drawback of the Ohling device is that the change in the direction of airflow is accomplished with the use of dampers, which introduce a reliability risk and a maintenance cost.
What is called for is an apparatus and method for the cooling of produce which allows for high volume through put, changes in direction in cooling air flow with a high reliability system, and seals which allow for sufficient latitude in container and pallet size and quantity to accommodate today's differing demands.